The longitudinalis inferior muscle belongs to the internal tongue muscles. Its fibers extend longitudinally through the tongue causing different tongue movements. Hypoglossal paralysis causes the longitudinal muscle to collapse with other tongue muscles, usually causing swallowing and speech problems.

What is the longitudinal muscle inferior?

The longitudinalis inferior muscle is located in the tongue, which is why the anatomy counts it among the internal tongue muscles. Its structure is not clearly differentiated from the other muscles in this group.

Instead, the internal tongue muscles form a mesh that can be roughly subdivided into layers according to the location and orientation of the fibers. The longitudinalis inferior muscle embodies the lower longitudinal fibers of the tongue. The upper longitudinal fibers, on the other hand, correspond to the superior longitudinal muscle. The other two tongue muscles represent the transversus linguae muscle and the verticalis linguae muscle.

In addition to the internal tongue muscles, people also have an external tongue muscles. These are the hyoglossal, genioglossal, styloglossus, palatoglossal and chondroglossal muscles. All tongue muscles are composed of striated fibers and belong to the skeletal musculature.

Anatomy & Construction

The origin of the longitudinal inferior muscle is located at the root of the tongue. This is also known as Radix linguae and is located at the rear end of the tongue, which faces the pharynx. At the base, some fibers of the longitudinal muscle inferior mix with fibers of the styloglossus muscle. This external tongue muscle spans between the hyoid bone (hyoid bone) and the tongue. Individual fibers of the longitudinal muscle inferior are also connected to the hyoid bone.

The longitudinal inferior muscle extends longitudinally from the root of the tongue through the tongue and attaches to the tip (Apex linguae). There, its fibers meet the genioglossus muscle, which protrudes from the lower jaw into the tongue as a chin and tongue muscle.

As a striated skeletal muscle, the longitudinal inferior muscle consists of segments (sarcomeres) that recur within the individual fibers. Protein filaments are arranged alternately therein. The filaments are structures of myosin as well as complexes of actin and tropomyosin. As the muscle tightens, these filaments move together, shortening the muscle fibers.

Function & Tasks

The longitudinal muscle inferior has the task of raising the tip of the tongue. In addition, he is able to shorten the tongue and arch. The longitudinalis inferior muscle acts as an antagonist of the transversus linguae muscle and the verticalis linguae muscle. However, it usually interacts with the longitudinal superior muscle because its fibers follow a similar course through the tongue and perform the same functions.

The longitudinal muscle inferior receives nerve signals from the hypoglossal nerve, also known as the tenth cranial nerve. Its core lies in the central nervous system in the extended medulla (medulla oblongata). The hypoglossal nerve drains from the skull into the neck through the hypoglossal canal (Canalis nervi hypoglossi). All tongue muscles except the palatoglossal muscle receive their orders to contract over the tenth cranial nerve. The nerve fibers represent the long processes of individual nerve cells and transport information in the form of electrical impulses. Motor nerve tracts open on the muscle in a motor end plate where the nerve signal passes from the neuronal fiber to the muscle.

Together with the other internal and external tongue muscles, the longitudinal muscle inferior controls the movements of the tongue. He supports chewing by repeatedly pushing food from the middle of the mouth to the teeth. In addition, the tongue helps with swallowing and supports the articulation of sounds. The tongue plays a particularly important role in the formation of the lingual (tongue sounds).

Diseases

In a stroke, hypoglossal nerve failure may occur if the circulatory disorder in the brain affects the cranial nerve central area.

The nucleus of the hypoglossal nerve lies in the medulla oblongata, which contains the neurons responsible for the motor control of the longitudinal inferior muscle and most other tongue muscles. As a rule, a stroke leads to unilateral failure of the hypoglossal nerve. Sufferers often experience dysphagia and speech disorders, as hypoglossal paralysis restricts the functioning of the tongue. Symptomatically the tongue shifts to one side. While the tongue is in the mouth, it gives way to the side that is not disturbed by the stroke. However, when the patient sticks out his tongue, he leans toward the damaged side.

In addition, a stroke often results in numerous other symptoms. These include sensory disturbances, confusion, dizziness, nausea, vomiting, blurred vision, headache, word finding disorders, neglect, difficulty in orientation, coordination and / or walking. In addition, individual extremities, a body side or the face may be paralyzed. Not all ailments must occur together and additional symptoms are possible. In a stroke, rapid treatment is required to stem the damage to the brain caused by the circulatory disorder.

The hypoglossal paralysis and thus a failure of the tongue muscles is not always associated with a stroke. Other possible causes include tumors, inflammation and dementia. Ulcers and inflammation do not have to occur in the brain, but can also occur in the later course of the hypoglossal nerve and impair its function. In addition, nerve lesions in severe head injuries are possible.

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